SodSAR: A Tower-Based 1–10 GHz SAR System for Snow, Soil and Vegetation Studies

Abstract

We introduce SodSAR, a fully polarimetric tower-based wide frequency (1–10 GHz) range Synthetic Aperture Radar (SAR) aimed at snow, soil and vegetation studies. The instrument is located in the Arctic Space Centre of the Finnish Meteorological Institute in Sodankylä, Finland. The system is based on a Vector Network Analyzer (VNA)-operated scatterometer mounted on a rail allowing the formation of SAR images, including interferometric pairs separated by a temporal baseline. We present the description of the radar, the applied SAR focusing technique, the radar calibration and measurement stability analysis. Measured stability of the backscattering intensity over a three-month period was observed to be better than 0.5 dB, when measuring a target with a known radar cross section. Deviations of the estimated target range were in the order of a few cm over the same period, indicating also good stability of the measured phase. Interforometric SAR (InSAR) capabilities are also discussed, and as a example, the coherence of subsequent SAR acquisitions over the observed boreal forest stand are analyzed over increasing temporal baselines. The analysis shows good conservation of coherence in particular at L-band, while higher frequencies are susceptible to loss of coherence in particular for dense vegetation. The potential of the instrument for satellite calibration and validation activities is also discussed.

Hybrid Deflection of Spoiler Influencing Radar Cross-Section of Tailless Fighter

“…A small aspect ratio duck-type flying wing aerodynamic layout is therefore presented [24]. The influence of actions including canards and spoilers on the dynamic RCS of the aircraft is yet to be resolved [25,26]. Considering that the modern aircraft is accompanied by complex flow field interference during the high angle of attack post-stall maneuvering, diversified design of control surface and intelligent flight control also face more challenges [27].…”